Telescoping jib assembly

ABSTRACT

A multisection extensible and retractable jib assembly is disclosed in this application. The jib assembly has a base section, at least one intermediate section and an outer section with means for extending and retracting the jib sections. The extending and retracting means includes a single cable having opposite ends connected to the outer section of the jib assembly and a reversible drive means operating with an intermediate portion of the cable and connected to the inner end of the base section of the jib assembly. A pair of pulleys are located on opposite ends of each intermediate section and one pulley is located on the outer end of the base section with the pulleys being positioned so that all of the cable portions between each pair of pulleys and the portion extending from the base section to the outer end section extends substantially parallel to each other and substantially parallel to the longitudinal axis of the jib assembly.

United States Patent 1 Lamer TELESCOPING JIB ASSEMBLY [75] Inventor:Gerald P. Lamer, Rothschild, Wis.

[73] Assignee: J. 1. Case Company, Racine, Wis.

[22] Filed: Nov. 29, 1973 [21] Appl. No.: 420,011

[52] US. Cl 212/55, 212/144, 214/141 [51] Int. Cl. B66c 23/06 [58] Fieldof Search 214/141, 146.5, 730; 187/9; 212/52, 144, 53, 54, 55; 254/139,147, 148

[56] References Cited UNITED STATES PATENTS 2,896,750 7/1959 Eitel212/55 3,044,312 7/1962 Hall et a1. 212/55 3,414,086 12/1968 Ulinski187/9 3,534,867 10/1970 Johnston et al 212/55 3,565,217 2/1971 St. Louis187/27 3,732,988 5/1973 Lamer 212/144 Primary Examiner-Robert J. SparAssistant Examiner-Lawrence J. Oresky Attorney, Agent, or Firm-Dressler,Goldsmith, Clement & Gordon, Ltd.

[ Oct. 29, 1974 [5 7] ABSTRACT A multisection extensible and retractablejib assembly is disclosed in this application. The jib assembly has abase section. at least one intermediate section and an outer sectionwith means for extending and retracting the jib sections. The extendingand retracting means includes a single cable having opposite endsconnected to the outer section of the jib assem bly and a reversibledrive means operating with an intermediate portion of the cable andconnected to the inner end of the base section of the jib assembly. Apair of pulleys are located on opposite ends of each intermediatesection and one pulley is located on the outer end of the base sectionwith the pulleys being positioned so that all of the cable portionsbetween each pair of pulleys and the portion extending from the basesection to the outer end section extends substantially parallel to eachother and substantially parallel to the longitudinal axis of the: jibassembly.

3 Claims, 3 Drawing lFigures BACKGROUND OF THE INVENTION A The presentinvention relates generally to multisection telescoping jib assemblies.One type of jib assembly that has recently been developed is disclosedin US. Pat. No. 3,732,988, assigned to the assignee of the presentinvention.

For many years, jib assemblies that were adapted to be attached to theouter end of a boom were of a fixed length. In recent years, it has beenproposed to make the jib assembly with a plurality of sections that canbe extended and retracted relative to each other to vary the effectivelength of the jib. Multisection jib assemblies of this type aredisclosed in the above mentioned patent as well as Noll, et al., US.Pat. No. 3,246,769.

All of the multisection jib assemblies commercially available today mustbe manually extended and retracted. This operation is not only extremelytime consuming for the operator but in some instances is extremelydifficult particularly when the jib assembly is of substantial lengthwhich results in a considerable amount of weight for each of thesections.

SUMMARY OF THE INVENTION The present invention contemplates anextensible and retractable multisection jib assembly in which the jibassembly has power driven extension and retraction means that arecompletely self-contained on the jib as sembly so that the entire jibassembly can be removed from the supporting crane, if desired.

The extension and retraction means consists of a single cable that hasopposite ends attached to the outer end section of the jib assembly andentrained over a pair of pulleys respectively located at opposite endsof each intermediate section and a single pulley carried by the outerend of the base section with the inner end of the base sectionsupporting reversible drive means cooperating with an intermediateportion of the cable. The drive means and the respective pulleys arearranged such that the cable has a portion for each intermediate sectionand each base section that extends substantially the entire length ofthe section as well as a further cable portion that extends from theinner end of the base section to the outer end section. The re spectivecable portions all extend substantially parallel to each other andparallel to the longitudinal axis and are also all located within thehollow sections. This arrangement will prevent developing any bendingforces for the respective jib section which may cause the sections tojam and prevent extension and retraction.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is sideview of a self-propelled crane having the jib assembly of the presentinvention supported thereon;

FIG. 2 is a schematic illustration of the extensible and retractabledrive means for the various jib sections with the sections being shownin phantom; and

FIG. 3 is a view similar to FIG. 2 showing only the base section of thejib assembly and a slightly modified arrangement between the reversibledrive means and the cable.

DETAILED DESCRIPTION While this invention is susceptible of embodimentin many different forms, there is shown in the drawings and will hereinbe described in detail preferred embodiments of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiments illustrated.

Referring to FIG. 1 of the drawings, jib assembly 10 is shown inconjunction with a vehicle 12 having a multisection boom 14, the innersection of which is pivoted about a horizontal axis on a turntable 16,forming part of the vehicle. Jib assembly 10 includes a base or innersection 20, at least one intermediate section 22 and an outer endsection 24. Each of the sections are of a polygonal or rectangularcross-sectional configuration and are hollow so that the respectivesections can telescope relative to each other for movement betweenextended and retracted positions. While the jib assembly need not belimited to any specific type of construction, it is preferred that theconstruction be of the lattice type disclosed in the above mentionedpatent assigned to the assignee of this invention.

In normal practice, the jib assembly is pivotally supported on a pin 26carried on the outer end of the outer boom section 14a and jib assembly10 is held in a substantially fixed position by a cable 28 that passesover a mast structure 30 carried on the outer end of outer boom section14a. The cable 28 and mast structure 30 may be of the type disclosed inthe above mentioned patent.

The various boom sections 20, 22, and 24 are extended and retracted withrespect to each other by an extending and retracting mechanism or meansthatis shown in FIG. 2. The extending and retracting mechanism consistsof a fixed length flexible cable 32 that has one end connected at 34 tothe inner end of the outer section 24. The opposite end of cable 32 isalso connected at 36 to the outer end section 24, adjacent the inner endthereof. Cable 32 is entrained over a pair of pulleys 38 and 40respectively freely rotatable on brackets 42 fixed to opposite ends ofeach of the intermediate sections 22. Cable 32 also is entrained over afurther pulley 44 that is freely rotatable on a bracket 46 locatedadjacent the outer end base section 20. Cable 32 has an intermediateportion cooperating with a reversible drive means 50 that is supportedat the inner end of base section 20 adjacent boom 14.

In the embodiment illustrated in FIG. 2, reversible drive means consistsof a drive motor 52 that is connected to a drum 54 through a drive belt56. In this embodiment, motor 52 and drum 54 are fixed to the uppersurface of base section 20 adjacent the inner end thereof by suitablebrackets (not shown).

The reversible drive means also incorporates three idler pulleys 58, 60and 62, all rotatable on the inner end of base section 22 and supportedby brackets not shown. Cable 32 is entrained over each of the idlerpulleys 58, 60 and 62 and the idler pulleys are utilized for changingthe direction of the intermediate portion of cable 32 so as to extendaround drum 54. If desired, cable 32 may be wound around drum severaltimes to increase the driving force between drum 54 and cables 32.

As can be seen from an inspection of FIG. 2, cable 32 has a firstportion 32a that is located inside hollow intermediate section 22 andextends between pulleys 38 and 40 on opposite ends of intermediatesection 22, cable 32 has a second cable portion 32b located insidehollow base section 20 and extending substantially the entire length ofbase section 20, cable 32 has a further portion 320 that extends fromouter end section 24 through hollow intermediate section and basesection to the inner end of base section 20. All of the cable portions,and in fact the entire cable except a small portion that cooperates withthe drive means 50 is located within the respective jib sections andcable portions 32a, 32b and 32c all extend substantially parallel toeach other and parallel to the longitudinal axis of jib assembly.Furthermore, the entire extension and retraction mechanism is completelyself-contained within the confines of jib assembly so that the entirejib assembly can readily be removed without the necessity ofdisassembling the extension and retraction mechanism.

A slightly modified form of the reversible drive mechanism is shown inFIG. 3 wherein only the base section has been illustrated. It will beunderstood that the remaining sections as well as the cable portionscooperating therewith are identical in construction and connection asshown in FIG. 2.

In the embodiment illustrated in H6. 3, all of the idler pulleys, 58, 60and 62 are deleted and reversible drive motor 52 as well as drum 54 anddrive belt 56 are located wtihin base section 20 and the cable extendsdirectly from pulley 44 on the outer end of base section 20 around drum54 and then from drum 54 directly to the outer section 24 where it isconnected at 36 to the outer section. With this arrangement, the entireextension and retraction mechanism or means, including the reversibledrive mechanism may be located inside the hollow boom section.

The advantage of having all of the cable portions 32a, 32b and 32clocated inside of the hollow boom section will reduce the possiblity ofthe cable becoming entangled in any adjacent equipment. In addition,having all of the cable portions extending substantially parallel toeach other and located inside the various jib sections and extendingparallel to the longitudinal axis of the jib assembly wll result inhaving all of the extending and retracting forces applied generallyparallel to the longitudinal axis of the boom. This will substantiallydecrease if not eliminate any bending motion that may be developed, iffor example, the cable portion 320 were located at an angle with respectto the longitudinal axis of the jib assembly. This bending action couldin some instances cause jamming of the boom sections to prevent relativemovement, particularly when the jib assembly is being retracted.

While any type of reversible drive mechanism 52 may be utilized. it ispreferable that the reversible motor be a hydraulic motor havinghydraulic fluid supplied from a source (not shown) on turntable l6.Alternately, the motor could be a completely self-contained unit, whichwould eliminate the need for having any connection between the turntable16 and the jib assembly 10 for providing power to motor 52. The motorcould, for example, be of the type that is driven by a rechargeablebattery.

What is claimed is:

1. An extensible jib assembly for attachment to the outer end of a boomand comprising a plurality of hollow jib sections telescoped within eachother for longitudinal extension and retraction to lengthen and shortenthe jib assembly, one of said sections being a base section having aninner end adapted for attachment to a boom and another of said sectionsbeing an outer end section with at least one intermediate sectionbetween said base section and said outer end section, and means forextending and retracting said sections, said means including a pair offreely rotatable pulleys adjacent opposite ends of each intermediatesection and a freely rotatable pulley adjacent an outer end of said basesection, reversible drive means carried by the inner end of said basesection, and a fixed length flexible cable having one end connected aninner end of said outer end section and entrained around each of saidpulleys, an intermediate portion of said cable being in engagement withsaid reversible drive means and an opposite end of said cable beingconnected to said outer section, said cable having portions for eachintermediate and base sections and one portion extending from said innerend of said base section to said outer end section, all of said portionsbeing located with said hollow sections and extending substantiallyparallel to each other and parallel to the longitudinal axis of said jibassembly.

2. An extensible jib assembly as defined in claim 1, in which said drivemeans includes a driven drum on said inner end of said base section anda plurality of idler pulleys on the inner end of said base section.

3. An extensible jib assembly as defined in claim 1, in which saidreversible drive means is located inside said hollow base section.

1. An extensible jib assembly for attachment to the outer end of a boomand comprising a plurality of hollow jib sections telescoped within eachother for longitudinal extension and retraction to lengthen and shortenthe jib assembly, one of said sections being a base section having aninner end adapted for attachment to a boom and another of said sectionsbeing an outer end section with at least one intermediate sectionbetween said base section and said outer end section, and means forextending and retracting said sections, said means including a pair offreely rotatable pulleys adjacent oppositE ends of each intermediatesection and a freely rotatable pulley adjacent an outer end of said basesection, reversible drive means carried by the inner end of said basesection, and a fixed length flexible cable having one end connected aninner end of said outer end section and entrained around each of saidpulleys, an intermediate portion of said cable being in engagement withsaid reversible drive means and an opposite end of said cable beingconnected to said outer section, said cable having portions for eachintermediate and base sections and one portion extending from said innerend of said base section to said outer end section, all of said portionsbeing located with said hollow sections and extending substantiallyparallel to each other and parallel to the longitudinal axis of said jibassembly.
 2. An extensible jib assembly as defined in claim 1, in whichsaid drive means includes a driven drum on said inner end of said basesection and a plurality of idler pulleys on the inner end of said basesection.
 3. An extensible jib assembly as defined in claim 1, in whichsaid reversible drive means is located inside said hollow base section.